Energy-band structure and Fermi surface of calcium by the orthogonalized plane wave method

Abstract

The energy-band structure of calcium has been calculated at the symmetry points Γ, W, X, L and K, along the symmetry axes Λ, Δ and Σ, and along the lines Z and Q inside the Brillouin zone. The convergence obtained for the orthogonalized plane wave expansions have been found to be quite satisfactory. The results obtained show a large band gap at the symmetry point X and a small gap at the symmetry point L. Another important feature of the investigation is that the lowest energy at the symmetry point W is lower than the lowest energy at the symmetry point K indicating dismembering of the connected Fermi surface of Harrison into pockets of holes around the symmetry point K. Approximate electron and hole surfaces have been drawn and de Haas-van Alphen orbits obtained from these curves have been compared with the experimental results of Condon and Marcus. The agreement is quite satisfactory